There is known in the art a method and apparatus for powder scarfing of metal, wherein flux fed from a flux-supply source is injected directly into a jet of oxygen delivered under high pressure to protect the metal being treated.
The flux-oxygen mixture passes through a central channel provided in the body of the powder scarfing apparatus, and then to the metal treating zone.
The flux is heated in the jet of burning oxygen, where it is melted and then is passed onto the metal surface to form a molten bath in the treating zone (see a book by O. Sh. Spectre entitled "Flux-Oxygen Torch Cutting of Stainless Steels", published in 1969 by Mashinostroenie Publishers, Moscow, p.76).
There is also known a method and apparatus for powder scarfing of metal, wherein flux is supplied from an outside source. In this case the flux is supplied by means of a flux-carrier gas through a heating flame of the apparatus and further into the jet of oxygen affording protection to metal.
The molten flux is passed in the mixture of gases into the metal treating zone.
In the apparatus used for carrying into effect the above method, flux is supplied by means of a flux-carrier gas to the metal treating zone from a flux adapter positioned above the body formed with oxygen and flux supply channels (see a book by Brandshtedt, entitled "Flux-Oxygen Deep and Surface Cutting of Metals", published in 1961 By Mashinostroenie Publishers, Moscow, p.75).
However, the powder scarfing methods described above are disadvantageous in that they allow an appreciable amount of flux to be lost due to high speed of its delivery. For the same reason, the part of the flux that gets to the metal treating zone is not kept there for sufficient time to be heated to a kindling temperature, which prevents its participation in the combustion process. As a result, the consumption of flux is substantially increased.
The prior art teaches another method and apparatus for powder scarfing of metal (see a book by B. Brandshtedt, entitled "Flux-Oxygen Deep and Surface Cutting of Metals", published in 1961 by Mashinostroenie Publishers, Moscow, p.40), wherein oxygen and combustible gas, required to form a heating flame and to effect the metal treating operation, are fed to the metal treating zone onto the metal surface. Then, flux, delivered by means of a flux-carrier gas from a flux source, is introduced through the heating flame into the jet of oxygen. Once in the heating flame, the flux is heated and melted therein, whereafter it is passed together with the metal-scarfing oxygen to the metal treating zone to form a molten bath therein.
The apparatus for performing the above-described method comprises a body with an oxygen supply channel formed in the central portion thereof. Provided in the body around the above channel is an annular orifice through which passes the oxygen-gas mixture on its way to the heating flame.
Flux is supplied by means of a flux-carrier gas to the metal treating zone through channels formed in the body of the apparatus around the annular opening and spaced at an angle to the axis of the central opening.
It should be observed that in the above method the flux-carrier gas tends to lower the degree of oxygen purity, which, in turn, impairs the flux melting process. Due to a high rate of flux delivery, an appreciable amount thereof fails to reach the metal treating zone while flying past it. For the same reason, a part of the flux mass is not heated to a metal melting temperature, with the resultant increase in the consumption of flux and oxygen. In addition, it takes considerable amount of time to form a bath of molten metal.